DETERMINATION OF CRITICAL PATH IN FUZZY NETWORK DIAGRAMS

Abstract

The classical critical path method (CPM) is characterized by a deterministic expression of the duration of activities in the network plan. When it comes to planning projects in the field of construction, it is especially difficult, and in some cases even impossible, to accurately predict or determine the duration of certain activities. The occurrence of uncertainty and inaccuracy in the duration of construction activities entails an imprecise determination of the total duration of the project's implementation. Often, in practice, there is a need for modelling of risks and uncertainties. This need arises from the fact that sometimes, depending on the specificity of the conditions in which certain construction activities are carried out, they cannot be defined with a precisely determined duration. The time of execution of the activities is usually conditioned by the uncertainty of the factors that have an impact on the activity. This is precisely why there is a need to apply fuzzy numbers in the process of planning and project management. This paper presents one example of application of Fuzzy logic in the process of planning and management of construction projects. The duration of construction activities is being analyzed in conditions of uncertainty and risk. Planning of construction process in cases where the durations of the activities, as part of the project, are given as fuzzy numbers is especially convenient in conditions of uncertainty and risk due to the great subjectivity that occurs during their assessment. Furthermore, this paper deals with the application of Fuzzy network planning technique. An overview of different procedures and methods for calculation of earliest and latest duration time of project activities will be given, and one specific method will be applied for determination of the critical path in fuzzy network diagram. The results of the conducted analyses show that this method can provide more realistic results thus more reliable planning of the construction time for the whole project.